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                    3.4：按钮
            
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                    3.5：图片和Icon
            
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                    3.6：单选框和复选框
            
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                    3.7：输入框和表单
            
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                    3.8：进度指示器
            
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                    第四章：布局类组件
            
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                    4.1：布局类组件简介
            
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                    4.2：线性布局（Row、Column）
            
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                    4.3：弹性布局（Flex）
            
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                    5.1：填充（Padding）
            
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                    5.2：尺寸限制类容器（ConstrainedBox等）
            
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                    5.3：装饰容器（DecoratedBox）
            
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                    5.4：变换（Transform）
            
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                    5.5：Container容器
            
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                    5.6：Scaffold、TabBar、底部导航
            
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                    5.7：剪裁（Clip）
            
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                    第六章：可滚动组件
            
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                    6.1：可滚动组件简介
            
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                    6.2：SingleChildScrollView
            
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                    6.3：ListView
            
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                    6.4：GridView
            
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                    6.5：CustomScrollView
            
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                    6.6：滚动监听及控制（ScrollController）
            
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                    第七章：功能型组件
            
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                    7.1：导航返回拦截（WillPopScope）
            
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                    7.2：数据共享（InheritedWidget）
            
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                    7.3： 跨组件状态共享（Provider）
            
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                    7.4：颜色和主题（Theme）
            
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                    7.5：异步UI更新（FutureBuilder、StreamBuilder）
            
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                    7.6：对话框详解
            
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        <li class="header">进阶篇</li>
        
        
    
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                    第八章：事件处理与通知
            
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                    8.1：原始指针事件处理
            
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                    8.2：手势识别
            
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        <li class="chapter " data-level="3.1.3" data-path="../chapter8/eventbus.html">
            
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                    8.3：全局事件总线
            
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                    8.4：通知(Notification)
            
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                    第九章：动画
            
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                    9.1：Flutter动画简介
            
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        <li class="chapter " data-level="3.2.2" data-path="../chapter9/animation_structure.html">
            
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                    9.2：动画结构
            
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                    9.3：自定义路由过渡动画
            
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                    9.4：Hero动画
            
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                    9.5：交织动画
            
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                    9.6：通用"切换动画"组件（AnimatedSwitcher）
            
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                    9.7：动画过渡组件
            
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                    第十章：自定义组件
            
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                    10.1：自定义组件方法简介
            
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                    10.2：组合现有组件
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.3.3" data-path="turn_box.html">
            
                <a href="turn_box.html">
            
                    
                    10.3：组合实例：TurnBox
            
                </a>
            

            
        </li>
    
        <li class="chapter active" data-level="3.3.4" data-path="custom_paint.html">
            
                <a href="custom_paint.html">
            
                    
                    10.4：自绘组件（CustomPaint与Canvas）
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.3.5" data-path="gradient_circular_progress_demo.html">
            
                <a href="gradient_circular_progress_demo.html">
            
                    
                    10.5：自绘实例：圆形渐变进度条(自绘)
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="3.4" data-path="../chapter11/">
            
                <a href="../chapter11/">
            
                    
                    第十一章：文件操作与网络请求
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="3.4.1" data-path="../chapter11/file_operation.html">
            
                <a href="../chapter11/file_operation.html">
            
                    
                    11.1：文件操作
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.4.2" data-path="../chapter11/http.html">
            
                <a href="../chapter11/http.html">
            
                    
                    11.2：Http请求-HttpClient
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.4.3" data-path="../chapter11/dio.html">
            
                <a href="../chapter11/dio.html">
            
                    
                    11.3：Http请求-Dio package
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.4.4" data-path="../chapter11/download_with_chunks.html">
            
                <a href="../chapter11/download_with_chunks.html">
            
                    
                    11.4：实例：Http分块下载
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.4.5" data-path="../chapter11/websocket.html">
            
                <a href="../chapter11/websocket.html">
            
                    
                    11.5：WebSocket
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.4.6" data-path="../chapter11/socket.html">
            
                <a href="../chapter11/socket.html">
            
                    
                    11.6：使用Socket API
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.4.7" data-path="../chapter11/json_model.html">
            
                <a href="../chapter11/json_model.html">
            
                    
                    11.7：Json转Dart Model类
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="3.5" data-path="../chapter12/">
            
                <a href="../chapter12/">
            
                    
                    第十二章：包与插件
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="3.5.1" data-path="../chapter12/develop_package.html">
            
                <a href="../chapter12/develop_package.html">
            
                    
                    12.1：开发package
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.5.2" data-path="../chapter12/platform-channel.html">
            
                <a href="../chapter12/platform-channel.html">
            
                    
                    12.2：平台通道简介
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.5.3" data-path="../chapter12/develop_plugin.html">
            
                <a href="../chapter12/develop_plugin.html">
            
                    
                    12.3：开发Flutter插件
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.5.4" data-path="../chapter12/android_implement.html">
            
                <a href="../chapter12/android_implement.html">
            
                    
                    12.4：插件开发：实现Android端API
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.5.5" data-path="../chapter12/ios_implement.html">
            
                <a href="../chapter12/ios_implement.html">
            
                    
                    12.5：插件开发：实现IOS端API
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.5.6" data-path="../chapter12/texture_platformview.html">
            
                <a href="../chapter12/texture_platformview.html">
            
                    
                    12.6：Texture和PlatformView
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="3.6" data-path="../chapter13/">
            
                <a href="../chapter13/">
            
                    
                    第十三章：国际化
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="3.6.1" data-path="../chapter13/multi_languages_support.html">
            
                <a href="../chapter13/multi_languages_support.html">
            
                    
                    13.1：让App支持多语言
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.6.2" data-path="../chapter13/locallization_implement.html">
            
                <a href="../chapter13/locallization_implement.html">
            
                    
                    13.2：实现Localizations
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.6.3" data-path="../chapter13/intl.html">
            
                <a href="../chapter13/intl.html">
            
                    
                    13.3：使用Intl包
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.6.4" data-path="../chapter13/faq.html">
            
                <a href="../chapter13/faq.html">
            
                    
                    13.4：国际化常见问题
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="3.7" data-path="../chapter14/">
            
                <a href="../chapter14/">
            
                    
                    第十四章：Flutter核心原理
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="3.7.1" data-path="../chapter14/flutter_ui_system.html">
            
                <a href="../chapter14/flutter_ui_system.html">
            
                    
                    14.1：Flutter UI系统
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.7.2" data-path="../chapter14/element_buildcontext.html">
            
                <a href="../chapter14/element_buildcontext.html">
            
                    
                    14.2：Element和BuildContext
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.7.3" data-path="../chapter14/render_object.html">
            
                <a href="../chapter14/render_object.html">
            
                    
                    14.3：RenderObject与RenderBox
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.7.4" data-path="../chapter14/flutter_app_startup.html">
            
                <a href="../chapter14/flutter_app_startup.html">
            
                    
                    14.4：Flutter从启动到显示
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="3.7.5" data-path="../chapter14/image_and_cache.html">
            
                <a href="../chapter14/image_and_cache.html">
            
                    
                    14.5：Flutter图片加载与缓存
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    

    
        
        <li class="header">实例篇</li>
        
        
    
        <li class="chapter " data-level="4.1" data-path="../chapter15/intro.html">
            
                <a href="../chapter15/intro.html">
            
                    
                    第十五章：一个完整的Flutter应用
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="4.1.1" data-path="../chapter15/intro.html">
            
                <a href="../chapter15/intro.html">
            
                    
                    15.1：应用简介
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="4.1.2" data-path="../chapter15/code_structure.html">
            
                <a href="../chapter15/code_structure.html">
            
                    
                    15.2：APP代码结构
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="4.1.3" data-path="../chapter15/models.html">
            
                <a href="../chapter15/models.html">
            
                    
                    15.3：Model类定义
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="4.1.4" data-path="../chapter15/globals.html">
            
                <a href="../chapter15/globals.html">
            
                    
                    15.4：全局变量及共享状态
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="4.1.5" data-path="../chapter15/network.html">
            
                <a href="../chapter15/network.html">
            
                    
                    15.5：网络请求封装
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="4.1.6" data-path="../chapter15/entry.html">
            
                <a href="../chapter15/entry.html">
            
                    
                    15.6：App入口及首页
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="4.1.7" data-path="../chapter15/login_page.html">
            
                <a href="../chapter15/login_page.html">
            
                    
                    15.7：登录页
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="4.1.8" data-path="../chapter15/language_and_theme_setting.html">
            
                <a href="../chapter15/language_and_theme_setting.html">
            
                    
                    15.8：多语言和多主题
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    

    

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                                <h1 id="104-&#x81EA;&#x7ED8;&#x7EC4;&#x4EF6;-&#xFF08;custompaint&#x4E0E;canvas&#xFF09;">10.4 &#x81EA;&#x7ED8;&#x7EC4;&#x4EF6; &#xFF08;CustomPaint&#x4E0E;Canvas&#xFF09;</h1>
<p>&#x5BF9;&#x4E8E;&#x4E00;&#x4E9B;&#x590D;&#x6742;&#x6216;&#x4E0D;&#x89C4;&#x5219;&#x7684;UI&#xFF0C;&#x6211;&#x4EEC;&#x53EF;&#x80FD;&#x65E0;&#x6CD5;&#x901A;&#x8FC7;&#x7EC4;&#x5408;&#x5176;&#x5B83;&#x7EC4;&#x4EF6;&#x7684;&#x65B9;&#x5F0F;&#x6765;&#x5B9E;&#x73B0;&#xFF0C;&#x6BD4;&#x5982;&#x6211;&#x4EEC;&#x9700;&#x8981;&#x4E00;&#x4E2A;&#x6B63;&#x516D;&#x8FB9;&#x5F62;&#x3001;&#x4E00;&#x4E2A;&#x6E10;&#x53D8;&#x7684;&#x5706;&#x5F62;&#x8FDB;&#x5EA6;&#x6761;&#x3001;&#x4E00;&#x4E2A;&#x68CB;&#x76D8;&#x7B49;&#x3002;&#x5F53;&#x7136;&#xFF0C;&#x6709;&#x65F6;&#x5019;&#x6211;&#x4EEC;&#x53EF;&#x4EE5;&#x4F7F;&#x7528;&#x56FE;&#x7247;&#x6765;&#x5B9E;&#x73B0;&#xFF0C;&#x4F46;&#x5728;&#x4E00;&#x4E9B;&#x9700;&#x8981;&#x52A8;&#x6001;&#x4EA4;&#x4E92;&#x7684;&#x573A;&#x666F;&#x9759;&#x6001;&#x56FE;&#x7247;&#x4E5F;&#x662F;&#x5B9E;&#x73B0;&#x4E0D;&#x4E86;&#x7684;&#xFF0C;&#x6BD4;&#x5982;&#x8981;&#x5B9E;&#x73B0;&#x4E00;&#x4E2A;&#x624B;&#x5199;&#x8F93;&#x5165;&#x9762;&#x677F;&#xFF0C;&#x8FD9;&#x65F6;&#xFF0C;&#x6211;&#x4EEC;&#x5C31;&#x9700;&#x8981;&#x6765;&#x81EA;&#x5DF1;&#x7ED8;&#x5236;UI&#x5916;&#x89C2;&#x3002;</p>
<p>&#x51E0;&#x4E4E;&#x6240;&#x6709;&#x7684;UI&#x7CFB;&#x7EDF;&#x90FD;&#x4F1A;&#x63D0;&#x4F9B;&#x4E00;&#x4E2A;&#x81EA;&#x7ED8;UI&#x7684;&#x63A5;&#x53E3;&#xFF0C;&#x8FD9;&#x4E2A;&#x63A5;&#x53E3;&#x901A;&#x5E38;&#x4F1A;&#x63D0;&#x4F9B;&#x4E00;&#x5757;2D&#x753B;&#x5E03;<code>Canvas</code>&#xFF0C;<code>Canvas</code>&#x5185;&#x90E8;&#x5C01;&#x88C5;&#x4E86;&#x4E00;&#x4E9B;&#x57FA;&#x672C;&#x7ED8;&#x5236;&#x7684;API&#xFF0C;&#x5F00;&#x53D1;&#x8005;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;<code>Canvas</code>&#x7ED8;&#x5236;&#x5404;&#x79CD;&#x81EA;&#x5B9A;&#x4E49;&#x56FE;&#x5F62;&#x3002;&#x5728;Flutter&#x4E2D;&#xFF0C;&#x63D0;&#x4F9B;&#x4E86;&#x4E00;&#x4E2A;<code>CustomPaint</code> &#x7EC4;&#x4EF6;&#xFF0C;&#x5B83;&#x53EF;&#x4EE5;&#x7ED3;&#x5408;&#x753B;&#x7B14;<code>CustomPainter</code>&#x6765;&#x5B9E;&#x73B0;&#x81EA;&#x5B9A;&#x4E49;&#x56FE;&#x5F62;&#x7ED8;&#x5236;&#x3002;</p>
<h3 id="custompaint">CustomPaint</h3>
<p>&#x6211;&#x4EEC;&#x770B;&#x770B;<code>CustomPaint</code>&#x6784;&#x9020;&#x51FD;&#x6570;&#xFF1A;</p>
<pre class="language-"><code class="lang-dart"><span class="token function">CustomPaint</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
  Key key<span class="token punctuation">,</span>
  <span class="token keyword">this</span><span class="token punctuation">.</span>painter<span class="token punctuation">,</span> 
  <span class="token keyword">this</span><span class="token punctuation">.</span>foregroundPainter<span class="token punctuation">,</span>
  <span class="token keyword">this</span><span class="token punctuation">.</span>size <span class="token operator">=</span> Size<span class="token punctuation">.</span>zero<span class="token punctuation">,</span> 
  <span class="token keyword">this</span><span class="token punctuation">.</span>isComplex <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">,</span> 
  <span class="token keyword">this</span><span class="token punctuation">.</span>willChange <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">,</span> 
  Widget child<span class="token punctuation">,</span> <span class="token comment">//&#x5B50;&#x8282;&#x70B9;&#xFF0C;&#x53EF;&#x4EE5;&#x4E3A;&#x7A7A;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
</code></pre>
<ul>
<li><code>painter</code>: &#x80CC;&#x666F;&#x753B;&#x7B14;&#xFF0C;&#x4F1A;&#x663E;&#x793A;&#x5728;&#x5B50;&#x8282;&#x70B9;&#x540E;&#x9762;;</li>
<li><code>foregroundPainter</code>: &#x524D;&#x666F;&#x753B;&#x7B14;&#xFF0C;&#x4F1A;&#x663E;&#x793A;&#x5728;&#x5B50;&#x8282;&#x70B9;&#x524D;&#x9762;</li>
<li><code>size</code>&#xFF1A;&#x5F53;child&#x4E3A;null&#x65F6;&#xFF0C;&#x4EE3;&#x8868;&#x9ED8;&#x8BA4;&#x7ED8;&#x5236;&#x533A;&#x57DF;&#x5927;&#x5C0F;&#xFF0C;&#x5982;&#x679C;&#x6709;child&#x5219;&#x5FFD;&#x7565;&#x6B64;&#x53C2;&#x6570;&#xFF0C;&#x753B;&#x5E03;&#x5C3A;&#x5BF8;&#x5219;&#x4E3A;child&#x5C3A;&#x5BF8;&#x3002;&#x5982;&#x679C;&#x6709;child&#x4F46;&#x662F;&#x60F3;&#x6307;&#x5B9A;&#x753B;&#x5E03;&#x4E3A;&#x7279;&#x5B9A;&#x5927;&#x5C0F;&#xFF0C;&#x53EF;&#x4EE5;&#x4F7F;&#x7528;SizeBox&#x5305;&#x88F9;CustomPaint&#x5B9E;&#x73B0;&#x3002;</li>
<li><code>isComplex</code>&#xFF1A;&#x662F;&#x5426;&#x590D;&#x6742;&#x7684;&#x7ED8;&#x5236;&#xFF0C;&#x5982;&#x679C;&#x662F;&#xFF0C;Flutter&#x4F1A;&#x5E94;&#x7528;&#x4E00;&#x4E9B;&#x7F13;&#x5B58;&#x7B56;&#x7565;&#x6765;&#x51CF;&#x5C11;&#x91CD;&#x590D;&#x6E32;&#x67D3;&#x7684;&#x5F00;&#x9500;&#x3002;</li>
<li><code>willChange</code>&#xFF1A;&#x548C;<code>isComplex</code>&#x914D;&#x5408;&#x4F7F;&#x7528;&#xFF0C;&#x5F53;&#x542F;&#x7528;&#x7F13;&#x5B58;&#x65F6;&#xFF0C;&#x8BE5;&#x5C5E;&#x6027;&#x4EE3;&#x8868;&#x5728;&#x4E0B;&#x4E00;&#x5E27;&#x4E2D;&#x7ED8;&#x5236;&#x662F;&#x5426;&#x4F1A;&#x6539;&#x53D8;&#x3002;</li>
</ul>
<p>&#x53EF;&#x4EE5;&#x770B;&#x5230;&#xFF0C;&#x7ED8;&#x5236;&#x65F6;&#x6211;&#x4EEC;&#x9700;&#x8981;&#x63D0;&#x4F9B;&#x524D;&#x666F;&#x6216;&#x80CC;&#x666F;&#x753B;&#x7B14;&#xFF0C;&#x4E24;&#x8005;&#x4E5F;&#x53EF;&#x4EE5;&#x540C;&#x65F6;&#x63D0;&#x4F9B;&#x3002;&#x6211;&#x4EEC;&#x7684;&#x753B;&#x7B14;&#x9700;&#x8981;&#x7EE7;&#x627F;<code>CustomPainter</code>&#x7C7B;&#xFF0C;&#x6211;&#x4EEC;&#x5728;&#x753B;&#x7B14;&#x7C7B;&#x4E2D;&#x5B9E;&#x73B0;&#x771F;&#x6B63;&#x7684;&#x7ED8;&#x5236;&#x903B;&#x8F91;&#x3002;</p>
<h4 id="&#x6CE8;&#x610F;">&#x6CE8;&#x610F;</h4>
<p>&#x5982;&#x679C;<code>CustomPaint</code>&#x6709;&#x5B50;&#x8282;&#x70B9;&#xFF0C;&#x4E3A;&#x4E86;&#x907F;&#x514D;&#x5B50;&#x8282;&#x70B9;&#x4E0D;&#x5FC5;&#x8981;&#x7684;&#x91CD;&#x7ED8;&#x5E76;&#x63D0;&#x9AD8;&#x6027;&#x80FD;&#xFF0C;&#x901A;&#x5E38;&#x60C5;&#x51B5;&#x4E0B;&#x90FD;&#x4F1A;&#x5C06;&#x5B50;&#x8282;&#x70B9;&#x5305;&#x88F9;&#x5728;<code>RepaintBoundary</code>&#x7EC4;&#x4EF6;&#x4E2D;&#xFF0C;&#x8FD9;&#x6837;&#x4F1A;&#x5728;&#x7ED8;&#x5236;&#x65F6;&#x5C31;&#x4F1A;&#x521B;&#x5EFA;&#x4E00;&#x4E2A;&#x65B0;&#x7684;&#x7ED8;&#x5236;&#x5C42;&#xFF08;Layer&#xFF09;&#xFF0C;&#x5176;&#x5B50;&#x7EC4;&#x4EF6;&#x5C06;&#x5728;&#x65B0;&#x7684;Layer&#x4E0A;&#x7ED8;&#x5236;&#xFF0C;&#x800C;&#x7236;&#x7EC4;&#x4EF6;&#x5C06;&#x5728;&#x539F;&#x6765;Layer&#x4E0A;&#x7ED8;&#x5236;&#xFF0C;&#x4E5F;&#x5C31;&#x662F;&#x8BF4;<code>RepaintBoundary</code> &#x5B50;&#x7EC4;&#x4EF6;&#x7684;&#x7ED8;&#x5236;&#x5C06;&#x72EC;&#x7ACB;&#x4E8E;&#x7236;&#x7EC4;&#x4EF6;&#x7684;&#x7ED8;&#x5236;&#xFF0C;<code>RepaintBoundary</code>&#x4F1A;&#x9694;&#x79BB;&#x5176;&#x5B50;&#x8282;&#x70B9;&#x548C;<code>CustomPaint</code>&#x672C;&#x8EAB;&#x7684;&#x7ED8;&#x5236;&#x8FB9;&#x754C;&#x3002;&#x793A;&#x4F8B;&#x5982;&#x4E0B;&#xFF1A;</p>
<pre class="language-"><code class="lang-dart"><span class="token function">CustomPaint</span><span class="token punctuation">(</span>
  size<span class="token punctuation">:</span> <span class="token function">Size</span><span class="token punctuation">(</span><span class="token number">300</span><span class="token punctuation">,</span> <span class="token number">300</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token comment">//&#x6307;&#x5B9A;&#x753B;&#x5E03;&#x5927;&#x5C0F;</span>
  painter<span class="token punctuation">:</span> <span class="token function">MyPainter</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
  child<span class="token punctuation">:</span> <span class="token function">RepaintBoundary</span><span class="token punctuation">(</span>child<span class="token punctuation">:</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">,</span> 
<span class="token punctuation">)</span>
</code></pre>
<h3 id="custompainter">CustomPainter</h3>
<p><code>CustomPainter</code>&#x4E2D;&#x63D0;&#x5B9A;&#x4E49;&#x4E86;&#x4E00;&#x4E2A;&#x865A;&#x51FD;&#x6570;<code>paint</code>&#xFF1A;</p>
<pre class="language-"><code>void paint(Canvas canvas, Size size);
</code></pre><p><code>paint</code>&#x6709;&#x4E24;&#x4E2A;&#x53C2;&#x6570;:</p>
<ul>
<li><p><code>Canvas</code>&#xFF1A;&#x4E00;&#x4E2A;&#x753B;&#x5E03;&#xFF0C;&#x5305;&#x62EC;&#x5404;&#x79CD;&#x7ED8;&#x5236;&#x65B9;&#x6CD5;&#xFF0C;&#x6211;&#x4EEC;&#x5217;&#x51FA;&#x4E00;&#x4E0B;&#x5E38;&#x7528;&#x7684;&#x65B9;&#x6CD5;&#xFF1A;</p>
<p>|API&#x540D;&#x79F0;     | &#x529F;&#x80FD;   |
| ---------- | ------ |
| drawLine   | &#x753B;&#x7EBF;   |
| drawPoint  | &#x753B;&#x70B9;   |
| drawPath   | &#x753B;&#x8DEF;&#x5F84; |
| drawImage  | &#x753B;&#x56FE;&#x50CF; |
| drawRect   | &#x753B;&#x77E9;&#x5F62; |
| drawCircle | &#x753B;&#x5706;   |
| drawOval   | &#x753B;&#x692D;&#x5706; |
| drawArc    | &#x753B;&#x5706;&#x5F27; |</p>
</li>
<li><p><code>Size</code>&#xFF1A;&#x5F53;&#x524D;&#x7ED8;&#x5236;&#x533A;&#x57DF;&#x5927;&#x5C0F;&#x3002;</p>
</li>
</ul>
<h3 id="&#x753B;&#x7B14;paint">&#x753B;&#x7B14;Paint</h3>
<p>&#x73B0;&#x5728;&#x753B;&#x5E03;&#x6709;&#x4E86;&#xFF0C;&#x6211;&#x4EEC;&#x6700;&#x540E;&#x8FD8;&#x7F3A;&#x4E00;&#x4E2A;&#x753B;&#x7B14;&#xFF0C;Flutter&#x63D0;&#x4F9B;&#x4E86;<code>Paint</code>&#x7C7B;&#x6765;&#x5B9E;&#x73B0;&#x753B;&#x7B14;&#x3002;&#x5728;<code>Paint</code>&#x4E2D;&#xFF0C;&#x6211;&#x4EEC;&#x53EF;&#x4EE5;&#x914D;&#x7F6E;&#x753B;&#x7B14;&#x7684;&#x5404;&#x79CD;&#x5C5E;&#x6027;&#x5982;&#x7C97;&#x7EC6;&#x3001;&#x989C;&#x8272;&#x3001;&#x6837;&#x5F0F;&#x7B49;&#x3002;&#x5982;&#xFF1A;</p>
<pre class="language-"><code class="lang-dart"><span class="token keyword">var</span> paint <span class="token operator">=</span> <span class="token function">Paint</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment">//&#x521B;&#x5EFA;&#x4E00;&#x4E2A;&#x753B;&#x7B14;&#x5E76;&#x914D;&#x7F6E;&#x5176;&#x5C5E;&#x6027;</span>
  <span class="token punctuation">.</span><span class="token punctuation">.</span>isAntiAlias <span class="token operator">=</span> <span class="token boolean">true</span> <span class="token comment">//&#x662F;&#x5426;&#x6297;&#x952F;&#x9F7F;</span>
  <span class="token punctuation">.</span><span class="token punctuation">.</span>style <span class="token operator">=</span> PaintingStyle<span class="token punctuation">.</span>fill <span class="token comment">//&#x753B;&#x7B14;&#x6837;&#x5F0F;&#xFF1A;&#x586B;&#x5145;</span>
  <span class="token punctuation">.</span><span class="token punctuation">.</span>color<span class="token operator">=</span><span class="token function">Color</span><span class="token punctuation">(</span><span class="token number">0x77cdb175</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//&#x753B;&#x7B14;&#x989C;&#x8272;</span>
</code></pre>
<p>&#x66F4;&#x591A;&#x7684;&#x914D;&#x7F6E;&#x5C5E;&#x6027;&#x8BFB;&#x8005;&#x53EF;&#x4EE5;&#x53C2;&#x8003;Paint&#x7C7B;&#x5B9A;&#x4E49;&#x3002;</p>
<h3 id="&#x793A;&#x4F8B;&#xFF1A;&#x4E94;&#x5B50;&#x68CB;&#x76D8;">&#x793A;&#x4F8B;&#xFF1A;&#x4E94;&#x5B50;&#x68CB;/&#x76D8;</h3>
<p>&#x4E0B;&#x9762;&#x6211;&#x4EEC;&#x901A;&#x8FC7;&#x4E00;&#x4E2A;&#x4E94;&#x5B50;&#x68CB;&#x6E38;&#x620F;&#x4E2D;&#x68CB;&#x76D8;&#x548C;&#x68CB;&#x5B50;&#x7684;&#x7ED8;&#x5236;&#x6765;&#x6F14;&#x793A;&#x81EA;&#x7ED8;UI&#x7684;&#x8FC7;&#x7A0B;&#xFF0C;&#x9996;&#x5148;&#x6211;&#x4EEC;&#x770B;&#x4E00;&#x4E0B;&#x6211;&#x4EEC;&#x7684;&#x76EE;&#x6807;&#x6548;&#x679C;&#xFF0C;&#x5982;&#x56FE;10-3&#x6240;&#x793A;&#xFF1A;</p>
<p><img src="https://cdn.jsdelivr.net/gh/flutterchina/flutter-in-action/docs/imgs/10-3.png" alt="&#x56FE;10-3"></p>
<p>&#x4EE3;&#x7801;&#xFF1A;</p>
<pre class="language-"><code class="lang-dart"><span class="token keyword">import</span> <span class="token string">&apos;package:flutter/material.dart&apos;</span><span class="token punctuation">;</span>
<span class="token keyword">import</span> <span class="token string">&apos;dart:math&apos;</span><span class="token punctuation">;</span>

<span class="token keyword">class</span> <span class="token class-name">CustomPaintRoute</span> <span class="token keyword">extends</span> <span class="token class-name">StatelessWidget</span> <span class="token punctuation">{</span>
  <span class="token metadata symbol">@override</span>
  Widget <span class="token function">build</span><span class="token punctuation">(</span>BuildContext context<span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> <span class="token function">Center</span><span class="token punctuation">(</span>
      child<span class="token punctuation">:</span> <span class="token function">CustomPaint</span><span class="token punctuation">(</span>
        size<span class="token punctuation">:</span> <span class="token function">Size</span><span class="token punctuation">(</span><span class="token number">300</span><span class="token punctuation">,</span> <span class="token number">300</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token comment">//&#x6307;&#x5B9A;&#x753B;&#x5E03;&#x5927;&#x5C0F;</span>
        painter<span class="token punctuation">:</span> <span class="token function">MyPainter</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
      <span class="token punctuation">)</span><span class="token punctuation">,</span>
    <span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token keyword">class</span> <span class="token class-name">MyPainter</span> <span class="token keyword">extends</span> <span class="token class-name">CustomPainter</span> <span class="token punctuation">{</span>
  <span class="token metadata symbol">@override</span>
  <span class="token keyword">void</span> <span class="token function">paint</span><span class="token punctuation">(</span>Canvas canvas<span class="token punctuation">,</span> Size size<span class="token punctuation">)</span> <span class="token punctuation">{</span>
    double eWidth <span class="token operator">=</span> size<span class="token punctuation">.</span>width <span class="token operator">/</span> <span class="token number">15</span><span class="token punctuation">;</span>
    double eHeight <span class="token operator">=</span> size<span class="token punctuation">.</span>height <span class="token operator">/</span> <span class="token number">15</span><span class="token punctuation">;</span>

    <span class="token comment">//&#x753B;&#x68CB;&#x76D8;&#x80CC;&#x666F;</span>
    <span class="token keyword">var</span> paint <span class="token operator">=</span> <span class="token function">Paint</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
      <span class="token punctuation">.</span><span class="token punctuation">.</span>isAntiAlias <span class="token operator">=</span> <span class="token boolean">true</span>
      <span class="token punctuation">.</span><span class="token punctuation">.</span>style <span class="token operator">=</span> PaintingStyle<span class="token punctuation">.</span>fill <span class="token comment">//&#x586B;&#x5145;</span>
      <span class="token punctuation">.</span><span class="token punctuation">.</span>color <span class="token operator">=</span> <span class="token function">Color</span><span class="token punctuation">(</span><span class="token number">0x77cdb175</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//&#x80CC;&#x666F;&#x4E3A;&#x7EB8;&#x9EC4;&#x8272;</span>
    canvas<span class="token punctuation">.</span><span class="token function">drawRect</span><span class="token punctuation">(</span>Offset<span class="token punctuation">.</span>zero <span class="token operator">&amp;</span> size<span class="token punctuation">,</span> paint<span class="token punctuation">)</span><span class="token punctuation">;</span>

    <span class="token comment">//&#x753B;&#x68CB;&#x76D8;&#x7F51;&#x683C;</span>
    paint
      <span class="token punctuation">.</span><span class="token punctuation">.</span>style <span class="token operator">=</span> PaintingStyle<span class="token punctuation">.</span>stroke <span class="token comment">//&#x7EBF;</span>
      <span class="token punctuation">.</span><span class="token punctuation">.</span>color <span class="token operator">=</span> Colors<span class="token punctuation">.</span>black87
      <span class="token punctuation">.</span><span class="token punctuation">.</span>strokeWidth <span class="token operator">=</span> <span class="token number">1.0</span><span class="token punctuation">;</span>

    <span class="token keyword">for</span> <span class="token punctuation">(</span>int i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;=</span> <span class="token number">15</span><span class="token punctuation">;</span> <span class="token operator">++</span>i<span class="token punctuation">)</span> <span class="token punctuation">{</span>
      double dy <span class="token operator">=</span> eHeight <span class="token operator">*</span> i<span class="token punctuation">;</span>
      canvas<span class="token punctuation">.</span><span class="token function">drawLine</span><span class="token punctuation">(</span><span class="token function">Offset</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> dy<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">Offset</span><span class="token punctuation">(</span>size<span class="token punctuation">.</span>width<span class="token punctuation">,</span> dy<span class="token punctuation">)</span><span class="token punctuation">,</span> paint<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token keyword">for</span> <span class="token punctuation">(</span>int i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;=</span> <span class="token number">15</span><span class="token punctuation">;</span> <span class="token operator">++</span>i<span class="token punctuation">)</span> <span class="token punctuation">{</span>
      double dx <span class="token operator">=</span> eWidth <span class="token operator">*</span> i<span class="token punctuation">;</span>
      canvas<span class="token punctuation">.</span><span class="token function">drawLine</span><span class="token punctuation">(</span><span class="token function">Offset</span><span class="token punctuation">(</span>dx<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">Offset</span><span class="token punctuation">(</span>dx<span class="token punctuation">,</span> size<span class="token punctuation">.</span>height<span class="token punctuation">)</span><span class="token punctuation">,</span> paint<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token comment">//&#x753B;&#x4E00;&#x4E2A;&#x9ED1;&#x5B50;</span>
    paint
      <span class="token punctuation">.</span><span class="token punctuation">.</span>style <span class="token operator">=</span> PaintingStyle<span class="token punctuation">.</span>fill
      <span class="token punctuation">.</span><span class="token punctuation">.</span>color <span class="token operator">=</span> Colors<span class="token punctuation">.</span>black<span class="token punctuation">;</span>
    canvas<span class="token punctuation">.</span><span class="token function">drawCircle</span><span class="token punctuation">(</span>
      <span class="token function">Offset</span><span class="token punctuation">(</span>size<span class="token punctuation">.</span>width <span class="token operator">/</span> <span class="token number">2</span> <span class="token operator">-</span> eWidth <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">,</span> size<span class="token punctuation">.</span>height <span class="token operator">/</span> <span class="token number">2</span> <span class="token operator">-</span> eHeight <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
      <span class="token function">min</span><span class="token punctuation">(</span>eWidth <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">,</span> eHeight <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">)</span> <span class="token operator">-</span> <span class="token number">2</span><span class="token punctuation">,</span>
      paint<span class="token punctuation">,</span>
    <span class="token punctuation">)</span><span class="token punctuation">;</span>

    <span class="token comment">//&#x753B;&#x4E00;&#x4E2A;&#x767D;&#x5B50;</span>
    paint<span class="token punctuation">.</span>color <span class="token operator">=</span> Colors<span class="token punctuation">.</span>white<span class="token punctuation">;</span>
    canvas<span class="token punctuation">.</span><span class="token function">drawCircle</span><span class="token punctuation">(</span>
      <span class="token function">Offset</span><span class="token punctuation">(</span>size<span class="token punctuation">.</span>width <span class="token operator">/</span> <span class="token number">2</span> <span class="token operator">+</span> eWidth <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">,</span> size<span class="token punctuation">.</span>height <span class="token operator">/</span> <span class="token number">2</span> <span class="token operator">-</span> eHeight <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
      <span class="token function">min</span><span class="token punctuation">(</span>eWidth <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">,</span> eHeight <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">)</span> <span class="token operator">-</span> <span class="token number">2</span><span class="token punctuation">,</span>
      paint<span class="token punctuation">,</span>
    <span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>

  <span class="token comment">//&#x5728;&#x5B9E;&#x9645;&#x573A;&#x666F;&#x4E2D;&#x6B63;&#x786E;&#x5229;&#x7528;&#x6B64;&#x56DE;&#x8C03;&#x53EF;&#x4EE5;&#x907F;&#x514D;&#x91CD;&#x7ED8;&#x5F00;&#x9500;&#xFF0C;&#x672C;&#x793A;&#x4F8B;&#x6211;&#x4EEC;&#x7B80;&#x5355;&#x7684;&#x8FD4;&#x56DE;true</span>
  <span class="token metadata symbol">@override</span>
  bool <span class="token function">shouldRepaint</span><span class="token punctuation">(</span>CustomPainter oldDelegate<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">&gt;</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre>
<h3 id="&#x6027;&#x80FD;">&#x6027;&#x80FD;</h3>
<p>&#x7ED8;&#x5236;&#x662F;&#x6BD4;&#x8F83;&#x6602;&#x8D35;&#x7684;&#x64CD;&#x4F5C;&#xFF0C;&#x6240;&#x4EE5;&#x6211;&#x4EEC;&#x5728;&#x5B9E;&#x73B0;&#x81EA;&#x7ED8;&#x63A7;&#x4EF6;&#x65F6;&#x5E94;&#x8BE5;&#x8003;&#x8651;&#x5230;&#x6027;&#x80FD;&#x5F00;&#x9500;&#xFF0C;&#x4E0B;&#x9762;&#x662F;&#x4E24;&#x6761;&#x5173;&#x4E8E;&#x6027;&#x80FD;&#x4F18;&#x5316;&#x7684;&#x5EFA;&#x8BAE;&#xFF1A;</p>
<ul>
<li><p>&#x5C3D;&#x53EF;&#x80FD;&#x7684;&#x5229;&#x7528;&#x597D;<code>shouldRepaint</code>&#x8FD4;&#x56DE;&#x503C;&#xFF1B;&#x5728;UI&#x6811;&#x91CD;&#x65B0;build&#x65F6;&#xFF0C;&#x63A7;&#x4EF6;&#x5728;&#x7ED8;&#x5236;&#x524D;&#x90FD;&#x4F1A;&#x5148;&#x8C03;&#x7528;&#x8BE5;&#x65B9;&#x6CD5;&#x4EE5;&#x786E;&#x5B9A;&#x662F;&#x5426;&#x6709;&#x5FC5;&#x8981;&#x91CD;&#x7ED8;&#xFF1B;&#x5047;&#x5982;&#x6211;&#x4EEC;&#x7ED8;&#x5236;&#x7684;UI&#x4E0D;&#x4F9D;&#x8D56;&#x5916;&#x90E8;&#x72B6;&#x6001;&#xFF0C;&#x90A3;&#x4E48;&#x5C31;&#x5E94;&#x8BE5;&#x59CB;&#x7EC8;&#x8FD4;&#x56DE;<code>false</code>&#xFF0C;&#x56E0;&#x4E3A;&#x5916;&#x90E8;&#x72B6;&#x6001;&#x6539;&#x53D8;&#x5BFC;&#x81F4;&#x91CD;&#x65B0;build&#x65F6;&#x4E0D;&#x4F1A;&#x5F71;&#x54CD;&#x6211;&#x4EEC;&#x7684;UI&#x5916;&#x89C2;&#xFF1B;&#x5982;&#x679C;&#x7ED8;&#x5236;&#x4F9D;&#x8D56;&#x5916;&#x90E8;&#x72B6;&#x6001;&#xFF0C;&#x90A3;&#x4E48;&#x6211;&#x4EEC;&#x5C31;&#x5E94;&#x8BE5;&#x5728;<code>shouldRepaint</code>&#x4E2D;&#x5224;&#x65AD;&#x4F9D;&#x8D56;&#x7684;&#x72B6;&#x6001;&#x662F;&#x5426;&#x6539;&#x53D8;&#xFF0C;&#x5982;&#x679C;&#x5DF2;&#x6539;&#x53D8;&#x5219;&#x5E94;&#x8FD4;&#x56DE;<code>true</code>&#x6765;&#x91CD;&#x7ED8;&#xFF0C;&#x53CD;&#x4E4B;&#x5219;&#x5E94;&#x8FD4;&#x56DE;<code>false</code>&#x4E0D;&#x9700;&#x8981;&#x91CD;&#x7ED8;&#x3002;</p>
</li>
<li><p>&#x7ED8;&#x5236;&#x5C3D;&#x53EF;&#x80FD;&#x591A;&#x7684;&#x5206;&#x5C42;&#xFF1B;&#x5728;&#x4E0A;&#x9762;&#x4E94;&#x5B50;&#x68CB;&#x7684;&#x793A;&#x4F8B;&#x4E2D;&#xFF0C;&#x6211;&#x4EEC;&#x5C06;&#x68CB;&#x76D8;&#x548C;&#x68CB;&#x5B50;&#x7684;&#x7ED8;&#x5236;&#x653E;&#x5728;&#x4E86;&#x4E00;&#x8D77;&#xFF0C;&#x8FD9;&#x6837;&#x4F1A;&#x6709;&#x4E00;&#x4E2A;&#x95EE;&#x9898;&#xFF1A;&#x7531;&#x4E8E;&#x68CB;&#x76D8;&#x59CB;&#x7EC8;&#x662F;&#x4E0D;&#x53D8;&#x7684;&#xFF0C;&#x7528;&#x6237;&#x6BCF;&#x6B21;&#x843D;&#x5B50;&#x65F6;&#x53D8;&#x7684;&#x53EA;&#x662F;&#x68CB;&#x5B50;&#xFF0C;&#x4F46;&#x662F;&#x5982;&#x679C;&#x6309;&#x7167;&#x4E0A;&#x9762;&#x7684;&#x4EE3;&#x7801;&#x6765;&#x5B9E;&#x73B0;&#xFF0C;&#x6BCF;&#x6B21;&#x7ED8;&#x5236;&#x68CB;&#x5B50;&#x65F6;&#x90FD;&#x8981;&#x91CD;&#x65B0;&#x7ED8;&#x5236;&#x4E00;&#x6B21;&#x68CB;&#x76D8;&#xFF0C;&#x8FD9;&#x662F;&#x6CA1;&#x5FC5;&#x8981;&#x7684;&#x3002;&#x4F18;&#x5316;&#x7684;&#x65B9;&#x6CD5;&#x5C31;&#x662F;&#x5C06;&#x68CB;&#x76D8;&#x5355;&#x72EC;&#x62BD;&#x4E3A;&#x4E00;&#x4E2A;&#x7EC4;&#x4EF6;&#xFF0C;&#x5E76;&#x8BBE;&#x7F6E;&#x5176;<code>shouldRepaint</code>&#x56DE;&#x8C03;&#x503C;&#x4E3A;<code>false</code>&#xFF0C;&#x7136;&#x540E;&#x5C06;&#x68CB;&#x76D8;&#x7EC4;&#x4EF6;&#x4F5C;&#x4E3A;&#x80CC;&#x666F;&#x3002;&#x7136;&#x540E;&#x5C06;&#x68CB;&#x5B50;&#x7684;&#x7ED8;&#x5236;&#x653E;&#x5230;&#x53E6;&#x4E00;&#x4E2A;&#x7EC4;&#x4EF6;&#x4E2D;&#xFF0C;&#x8FD9;&#x6837;&#x6BCF;&#x6B21;&#x843D;&#x5B50;&#x65F6;&#x53EA;&#x9700;&#x8981;&#x7ED8;&#x5236;&#x68CB;&#x5B50;&#x3002;</p>
</li>
</ul>
<h3 id="&#x603B;&#x7ED3;">&#x603B;&#x7ED3;</h3>
<p>&#x81EA;&#x7ED8;&#x63A7;&#x4EF6;&#x975E;&#x5E38;&#x5F3A;&#x5927;&#xFF0C;&#x7406;&#x8BBA;&#x4E0A;&#x53EF;&#x4EE5;&#x5B9E;&#x73B0;&#x4EFB;&#x4F55;2D&#x56FE;&#x5F62;&#x5916;&#x89C2;&#xFF0C;&#x5B9E;&#x9645;&#x4E0A;Flutter&#x63D0;&#x4F9B;&#x7684;&#x6240;&#x6709;&#x7EC4;&#x4EF6;&#x6700;&#x7EC8;&#x90FD;&#x662F;&#x901A;&#x8FC7;&#x8C03;&#x7528;Canvas&#x7ED8;&#x5236;&#x51FA;&#x6765;&#x7684;&#xFF0C;&#x53EA;&#x4E0D;&#x8FC7;&#x7ED8;&#x5236;&#x7684;&#x903B;&#x8F91;&#x88AB;&#x5C01;&#x88C5;&#x8D77;&#x6765;&#x4E86;&#xFF0C;&#x8BFB;&#x8005;&#x6709;&#x5174;&#x8DA3;&#x53EF;&#x4EE5;&#x67E5;&#x770B;&#x5177;&#x6709;&#x5916;&#x89C2;&#x6837;&#x5F0F;&#x7684;&#x7EC4;&#x4EF6;&#x6E90;&#x7801;&#xFF0C;&#x627E;&#x5230;&#x5176;&#x5BF9;&#x5E94;&#x7684;<code>RenderObject</code>&#x5BF9;&#x8C61;&#xFF0C;&#x5982;<code>Text</code>&#x5BF9;&#x5E94;&#x7684;<code>RenderParagraph</code>&#x5BF9;&#x8C61;&#x6700;&#x7EC8;&#x4F1A;&#x901A;&#x8FC7;<code>Canvas</code>&#x5B9E;&#x73B0;&#x6587;&#x672C;&#x7ED8;&#x5236;&#x903B;&#x8F91;&#x3002;&#x4E0B;&#x4E00;&#x8282;&#x6211;&#x4EEC;&#x4F1A;&#x518D;&#x901A;&#x8FC7;&#x4E00;&#x4E2A;&#x81EA;&#x7ED8;&#x7684;&#x5706;&#x5F62;&#x80CC;&#x666F;&#x6E10;&#x53D8;&#x8FDB;&#x5EA6;&#x6761;&#x7684;&#x5B9E;&#x4F8B;&#x6765;&#x5E2E;&#x52A9;&#x8BFB;&#x8005;&#x52A0;&#x6DF1;&#x5370;&#x8C61;&#x3002;</p>

                                
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